Computer-based data systems provide users with access to large data sets. For example, a data system can fulfill user requests for specified data, and cause presentation of the specified data to the user. While these types of computer-based data systems allow users to request and access data, they also require that a user repeatedly access a specified piece of data to determine whether modifications to the specified piece of data have occurred. This can be impractical when a user desires immediate notification that data has been modified and/or the user needs to monitor multiple pieces of data that would require executing multiple requests.